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Journal article

GacA-controlled activation of promoters for small RNA genes in Pseudomonas fluorescens.

  • Humair B Département de Microbiologie Fondamentale, Université de Lausanne, Bâtiment Biophore, CH-1015 Lausanne, Switzerland.
  • Wackwitz B
  • Haas D
  • 2010-01-06
Published in:
  • Applied and environmental microbiology. - 2010
Bacterial Proteins
Base Sequence
DNA, Bacterial
Electrophoretic Mobility Shift Assay
Gene Expression Regulation, Bacterial
Models, Biological
Molecular Sequence Data
Promoter Regions, Genetic
Protein Binding
Pseudomonas fluorescens
RNA, Bacterial
RNA, Untranslated
Transcriptional Activation
English The Gac/Rsm signal transduction pathway positively regulates secondary metabolism, production of extracellular enzymes, and biocontrol properties of Pseudomonas fluorescens CHA0 via the expression of three noncoding small RNAs, termed RsmX, RsmY, and RsmZ. The architecture and function of the rsmY and rsmZ promoters were studied in vivo. A conserved palindromic upstream activating sequence (UAS) was found to be necessary but not sufficient for rsmY and rsmZ expression and for activation by the response regulator GacA. A poorly conserved linker region located between the UAS and the -10 promoter sequence was also essential for GacA-dependent rsmY and rsmZ expression, suggesting a need for auxiliary transcription factors. One such factor involved in the activation of the rsmZ promoter was identified as the PsrA protein, previously recognized as an activator of the rpoS gene and a repressor of fatty acid degradation. Furthermore, the integration host factor (IHF) protein was found to bind with high affinity to the rsmZ promoter region in vitro, suggesting that DNA bending contributes to the regulated expression of rsmZ. In an rsmXYZ triple mutant, the expression of rsmY and rsmZ was elevated above that found in the wild type. This negative feedback loop appears to involve the translational regulators RsmA and RsmE, whose activity is antagonized by RsmXYZ, and several hypothetical DNA-binding proteins. This highly complex network controls the expression of the three small RNAs in response to cell physiology and cell population densities.
Language
  • English
Open access status
bronze
Identifiers
Persistent URL
https://sonar.ch/global/documents/27200
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